Method of manufacturing a semiconductor device isolated by a trench

Abstract

A manufacturing method of semiconductor devices and semiconductor devices isolated by a trench portion. The trench portion is refilled with a Si epitaxial growth layer. The trench has a first insulating layer on its side wall and a second insulating layer formed by the oxidation in the self-alignment manner, as a cap layer, on the top portion of the trench. A semiconductor device formed on the substrate is isolated by the trench. The excessive leakage currents created by the stress between the substrate and the Si epitaxial layer are decreased. The concentration of the field effect at the corner portion of the trench is suppressed by the cap layer. The refilling step can be also made to a trench having the wider opening and another trench having the narrower opening simultaneously and uniformly.

What is claimed is: 
     
       1. A manufacturing method for semiconductor devices, comprising the steps of: (a) etching a semiconductor substrate to form a trench having a side wall, an upper corner portion and a bottom surface on the substrate;   (b) forming an insulating layer on the side wall of the trench;   (c) refilling the trench with a semiconductor epitaxial growth layer;   (d) overfilling the upper corner portion of the trench with the epitaxial layer; and   (e) oxidizing the overfilled epitaxial growth layer, whereby an isolating portion to isolate semiconductor devices on the substrate is formed.   
     
     
       2. A manufacturing method for semiconductor devices according to claim 1, wherein the etching step includes forming a plurality of trenches having different widths. 
     
     
       3. A manufacturing method for semiconductor devices according to claim 2, wherein the refilling step includes refilling the trenches having the different widths simultaneously. 
     
     
       4. A manufacturing method for semiconductor devices according to claim 1, wherein refilling the trench is performed using a silicon epitaxial growth step. 
     
     
       5. A manufacturing method for semiconductor devices according to claim 4, wherein a temperature of 850°-900° C. is used during the growth step. 
     
     
       6. A manufacturing method for semiconductor devices according to claim 1, further comprising implanting ions through the oxidized layer. 
     
     
       7. A manufacturing method for semiconductor devices, comprising the steps of: (a) forming a first trench having a wider opening and a second trench having a narrower opening on a semiconductor substrate, wherein each of the first trench and the second trench has a side wall, an upper corner portion and a bottom   (b) forming an insulating layer on the side wall of the first trench and the second trench;   (c) refilling the first trench and the second trench with a semiconductor epitaxial growth layer;   (d) overfilling the upper corner portion of both of the trenches with the epitaxial layer simultaneously and uniformly to the same level in depth; and   (e) oxidizing the overfilled epitaxial growth layer, whereby at least two isolating portions to isolate semiconductor devices are formed at the first trench and the second trench.   
     
     
       8. A manufacturing method for semiconductor devices, comprising the steps of: (a) forming a first trench having a wider opening and a second trench having a narrower opening on a semiconductor substrate, wherein each of the first trench and the second trench has a side wall, an upper corner portion and a bottom surface respectively;   (b) forming an insulating layer on the side wall of the first trench to form a third opening and refilling the second trench with the insulating layer completely;   (c) refilling the third opening of the first trench with a semiconductor epitaxial growth layer completely; and   (d) oxidizing the refilled epitaxial growth layer, whereby at least two isolating portions to isolate semiconductor devices are formed at the first trench and the second trench.